On a blustery Saturday in early spring, when the tide is out and the air is heavy with the briny smell of the sea, Will Clyde hunkers down on a rocky outcropping, his back to the wind. He is intent on telling a story. The plot lines, he explains to a group of students clustered around him, are staring you in the face.

A dark bolt of basalt slices through the rough mass of gray rock beneath Clyde’s feet. The clue is obvious, but the story is complex. The assistant professor describes how the igneous intrusion, once a molten mass, cut through the older metamorphic rock. He asks a few questions. The students make notes. They are piecing together one small chapter of an ancient story, the history of the Earth.

Why care so much about the rock beneath our feet? “This is something I explain the first day of class,” says Clyde, who teaches Earth History, as well as Paleontology, and Sedimentary Rocks and Stratigraphy. “You should be interested in the history of the Earth for the same reason you’re interested in any history class: it puts our own existence in perspective.”

Back in his lab, the paleontologist holds a tiny cube of red stone between his thumb and forefinger. “This is the closest I get to art,” Clyde says, joking. But it’s true. Whenever he returns from the field—Wyoming or Alaska or Pakistan—Clyde spends hours bending over his mitre saw, grinding rough chunks of rock into perfect one-inch squares. It takes a certain deft touch not to cause a 50-million-year-old rock to disintegrate into useless crumbs.

Once they’re cut to size, each cube is labeled with a date, a site number, an identifying letter, and two arrows—one showing the “strike” or compass direction of the plane from which the rock was taken, the other indicating the “dip” or angle of the plane. Then Clyde gathers a batch of 30 samples and steps into a small metal cage—one of only a handful of paleomagnetism labs in the country. Inside this lab, a space free of Earth’s magnetic field, samples are repeatedly heated, cooled, and measured—a process that can take up to 60 hours per batch. The cumulative measurements help Clyde pinpoint a rock’s geological age.

Every cube offers another clue to help answer one of geology’s hottest questions: Where did modern mammals come from? “The evidence is so clear,” says Clyde, describing the striped rock formations of Wyoming’s Big Horn Basin, where he does much of his research. “At this one level, all of a sudden—wham! —you see all these modern mammals. Beneath this level, you don’t see any of them.”

It is this turning point, the boundary between the Paleocene and early Eocene epochs, that most intrigues Clyde.

—Suki Casanave,
College of Engineering
and Physical Sciences